• # question_answer Increasing value of magnetic moment of the following species is (i) ${{[Fe{{(CN)}_{6}}]}^{4-}}$ (ii) ${{[Fe{{(CN)}_{6}}]}^{3-}}$ (iii) ${{[Cr{{(N{{H}_{3}})}_{6}}]}^{3+}}$ (iv) ${{[Ni{{({{H}_{2}}O)}_{6}}]}^{2+}}$ A)  I < II < III < IV                      B)  IV < III < II < I C)  II < III < I < IV                      D)  I < II < IV < III

Magnetic moment $\propto$ number of unpaired electrons Number of unpaired electrons in the below species are (I) ${{[Fe{{(CN)}_{6}}]}^{4-}}=0;$       (II) ${{[Fe{{(CN)}_{6}}]}^{3-}}=1$ (III) ${{[Cr(N{{H}_{6}})]}^{3+}}=3;$   (IV) ${{[Ni{{({{H}_{2}}O)}_{6}}]}^{2+}}=2$ Hence, the correct order is I < II < IV < III